Assign symmetry operations (Inorganic Chemistry) to the following molecules 1

Assign symmetry operations (Inorganic Chemistry) to the following molecules 1. Binder Clip 2. I3- (including lone pairs) 3. PCl3F2 (isomers) 4. SF4 5. [PtCl3NH3]- (ignore Hs on N) square planar NH3 bonded through N Please explain how to do this.

The Correct Answer and Explanation is:

To assign symmetry operations to molecules in Inorganic Chemistry, follow these steps:

1. Determine the molecular geometry. Use VSEPR theory or known geometry for the molecule.
2. Visualize symmetry elements: These include:
   • Identity (E): present in all molecules.
   • Rotation axis (Cn): rotation by 360°/n gives an indistinguishable structure.
   • Mirror planes (σ): reflection symmetry.
   • Center of inversion (i).
   • Improper rotation (Sn): rotation followed by reflection through a plane perpendicular to the axis.

Now let’s apply these to the given molecules:

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1. Binder Clip
Though not a molecule, it has a well-defined geometry.

• Geometry: resembles a distorted triangular prism with metal arms.
• Symmetry:
  • E
  • A C2 axis through the clip’s center (perpendicular to the flat triangular base)
  • σv plane through the arms
  • Point group: C2v

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2. I₃⁻ (triiodide ion)

• Linear molecule with lone pairs on the terminal I atoms
• Symmetry operations:
  • E
  • C∞ axis (infinite-fold rotation)
  • ∞ σv planes (vertical)
  • i (inversion center at central I)
  • S∞ (improper axis)
  • Point group: D∞h

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3. PCl₃F₂

• Trigonal bipyramidal geometry
• Isomers:
  • Axial F atoms:
    • E, C3, 3 σv
    • Point group: D3h
  • Equatorial F atoms:
    • Lower symmetry
    • Only E and one σv
    • Point group: Cs

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4. SF₄

• Seesaw shape (AX₄E)
• Geometry lacks symmetry due to lone pair
• Symmetry elements:
  • E
  • C2 axis (through S and lone pair)
  • One σv plane (contains C2 and equatorial F atoms)
  • Point group: C2v

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5. [PtCl₃NH₃]⁻ (square planar)

• Geometry: square planar around Pt
• NH₃ occupies one position; Cl atoms the rest
• Symmetry:
  • E
  • One σv through NH₃ and opposite Cl
  • No C2 due to different ligand
  • Point group: Cs

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Summary:
Symmetry assignment involves identifying geometry, visualizing elements like rotation axes and mirror planes, and matching these to known point groups. This helps understand molecular vibrations, spectroscopy, and reactivity.